AGE OF PEERS AND EARLY-CHILDHOOD DEVELOPMENT

We examined the developmental trajectories of 59 children between 21 and 67 months of age randomly assigned to same-age or mixed-age child care groups. Children were assessed at 6-month intervals with the Battelle Developmental Inventory. Using a hierarchical linear model for analysis, we computed individual and group growth curves for overall development and development within 5 domains: communication, cognitive, motor, adaptive, and personal-social. Group assignment affected the developmental trajectories for communication, cognitive, motor, and overall development, with mixed-age children showing a quadratic trajectory and same-age children a linear trajectory. For adaptive and personal-social development, however, the trajectories were similar. Across all domains, the mixed-age children tended to score higher than the same-age children at the younger ages, but these average differences decreased over time and had disappeared by age 5 years.